The Hughes external fixation device: studies of its biomechanical properties' effect on fracture healing and its clinical application

External skeletal fixation devices first appeared in clinical practice in the 1850's. Their use has mainly been confined to Europe although North American surgeons developed an interest in the 1930's. In the last few years, however, there has been a reawakening of interest in external fixation in North America and Great Britain leading to a proliferation of different external fixation devices.Although some experimental work has been done on the biomechanics of some of the more complex fixators very little is known about the optimal configuration of application of most devices. Additionally there is scanty information on the effect that external fixation has on bone healing.This thesis examines the Hughes unilateral external fixator from three aspects.1) Its biomechanica1 properties are examined and the stiffest mode of application defined. The effects of altering this configuration are shown. A comparison is made with the Hoffmann device.2) The effect of external fixation on bone healing is examined. A small fixator is used to immobilise rabbit tibial osteotomies and the effect on healing and bone blood flow compared with an osteotomy treated with a cast.3) A prospective study of the clinical use of the Hughes fixator is presented. An analysis is made of the use of the device in treating tibial fractures.Biomechanical study: This was undertaken using beech as a bone substitute. A jig was constructed so that different loads could be applied to a simulated fracture held by a Hughes fixator. It was found that the stiffest configuration of the Hughes occurred with the fixator bar close to the limb. The inner pin should be as close to the fracture as possible with the outer pin as far from the fracture as is practical. The effect of altering the location of the bar from a lateral to an antero-media 1 location as used on the tibia was to lower the stiffness, although only to the level of stiffness gained using a Hoffmann-Vida 1 double frame. The effect of altering the stiffest configuration was examined.Bone healing and blood flow study: New Zealand white rabbits were used to investigate bone healing and blood flow using a small external fixator designed for the experiment. Bilateral tibial osteotomies were made and one was stabilised with the small fixator with the contra-1atera1 osteotomy being treated in a long-leg cast. After a period of between one and ten weeks the rabbits were sacrificed but prior to this were injected with radioactive microspheres. Comparison of the blood flow in the two fracture sites showed a considerable increase in flow in the cast-treated leg after four weeks.A review of the histology showed that external fixation altered bone healing. The externally fixed leg showed less periosteal reaction but enhanced endochondral ossification and intra-medullary ossification.Clinical study: A three year prospective study of the use of the Hughes fixator was undertaken. The device was mainly used for the treatment of tibial fractures although humeral fractures and pelvic diastases were also treated. In addition a number of osteotomies and an arthrodesis were stabilised with the device.A study of the tibial fractures showed that the eventual outcome of the fracture was dependent on the initial reduction and the length of time tha

Primary hemiarthroplasty for treatment of proximal humeral fractures

Background: Primary hemiarthroplasty of the shoulder is used to treat complex proximal humeral fractures, although the reported functional results following this method of treatment have varied widely. The aim of this study was to prospectively assess the prosthetic survival and functional outcomes in a large series of patients treated with shoulder hemiarthroplasty for a proximal humeral fracture. By determining the factors that affected the outcome, we also aimed to produce models that could be used clinically to estimate the functional outcome at one year following surgery.Methods: A thirteen-year observational cohort study of 163 consecutive patients treated with hemiarthroplasty for a proximal humeral fracture was performed. Twenty-five patients died or were lost to follow-up in the first year after treatment, leaving 138 patients who had assessment of shoulder function with use of the modified Constant score at one year postinjury.Results: The overall rate of prosthetic survival was 96.9% at one year, 95.3% at five years, and 93.9% at ten years. The overall median modified Constant score was 64 points at one year, with a typically good score for pain relief (median, 15 points) and poorer scores, with a greater scatter of values, for function (median, 12 points), range of motion (median, 24 points), and muscle power (median, 14 points). Of the factors that were assessed immediately after the injury, only patient age, the presence of a neurological deficit, tobacco usage, and alcohol consumption were significantly predictive of the one-year Constant score (p &lt; 0.05). Of the factors that were assessed at six weeks postinjury, those that predicted the one-year Constant score included the age of the patient, the presence of a persistent neurological deficit, the need for an early reoperation, the degree of displacement of the prosthetic head from the central axis of the glenoid seen radiographically, and the degree of displacement of the tuberosities seen radiographically.Conclusions: Primary shoulder hemiarthroplasty performed for the treatment of a proximal humeral fracture in medically fit and cooperative adults is associated with satisfactory prosthetic survival at an average of 6.3 years. Although the shoulder is usually free of pain following this procedure, the overall functional result, in terms of range of motion, function, and power, at one year varies. A good functional outcome can be anticipated for a younger individual who has no preoperative neurological deficit, no postoperative complications, and a satisfactory radiographic appearance of the shoulder at six weeks. The results are poorer in the larger group of elderly patients who undergo this procedure, especially if they have a neurological deficit, a postoperative complication requiring a reoperation, or an eccentrically located prosthesis with retracted tuberosities.<br /

Empirical Legal Studies Before 1940: A Bibliographic Essay

The modern empirical legal studies movement has well-known antecedents in the law and society and law and economics traditions of the latter half of the 20th century. Less well known is the body of empirical research on legal phenomena from the period prior to World War II. This paper is an extensive bibliographic essay that surveys the English language empirical legal research from approximately 1940 and earlier. The essay is arranged around the themes in the research: criminal justice, civil justice (general studies of civil litigation, auto accident litigation and compensation, divorce, small claims, jurisdiction and procedure, civil juries), debt and bankruptcy, banking, appellate courts, legal needs, legal profession (including legal education), and judicial staffing and selection. Accompanying the essay is an extensive bibliography of research articles, books, and reports

Students' participation in collaborative research should be recognised

Letter to the editor